Wang Xiaowei

Lateral Resolution and Signal to Noise Ratio in Electrostatic Force Detection Based on Scanning Probe Microscopy

The lateral resolution (LR) and signal-to-noise ratio (SNR) are the essential factors in the applications of scanning probe microscopy in quantitative measurement of surface charge distribution, potential profile, and dielectric properties. We use a model system to comprise Au nanoparticles (NPs) embedded in a polystyrene (PS) matrix to study the effects of various experimental parameters, such as modulation bias voltage, tip-sample distance, and actual tip shape, on the electrostatic interactions between the tips and samples. The results show that LR and SNR decrease when the tip-sample distance increases, while SNR increases with tip modulation voltage. LR is less sensitive to tip modulation voltage, but shows complex dependence on the sample geometric structure. In combination with a numerical simulation based on the integral capacitance model, the electrostatic force interaction between tip and sample was quantitatively analyzed.

Internal friction, shear modulus and magnetic susceptibility of lanthanum

The internal friction, relative shear modulus and magnetic susceptibility of La as a function of temperature have been observed in the range 80-700K. The mechanism of phase transformation FCC-double HCP of La is discussed.